Vehicle test stands having a pair of rollers operatively engageable by vehicle wheels are well known in the art. The test stand rollers may or may not be operatively connected to an energy conversion device. Vehicle test stands having the rollers connected to an energy conversion device include chassis dynamometers and vehicle brake testers.
In a chassis dynamometer, an actuatable power absorber is connected to the test stand roller pairs and applies a load force to a vehicle's drive wheels for testing purposes, such as pollution testing. A vehicle is driven onto the roller pairs of the test stand so that each drive wheel of the vehicle is straddled by an associated pair of rollers. Once positioned on the dynamometer, the vehicle's drive wheels are driven in rotation by the vehicle engine. The vehicle's drive wheels drive associated roller pairs into rotation. To load test the vehicle's engine, the power absorber is actuated to apply a braking force to the dynamometer rollers. This braking force on the vehicle's drive wheels effectively loads the vehicle's engine. Another form of chassis dynamometer includes a motor absorber connected to the test stand roller pair for selectively providing a braking or a driving force to the vehicle wheels.
In a brake tester, a drive motor is connected to the test stand rollers and applies a drive force to the vehicle wheels. A torque sensor is operatively connected to the test stand rollers and measures the torque developed when the vehicle brakes are applied. The measured torque is indicative of the vehicle's braking force.
Since substantial forces are present between the vehicle and the vehicle test stand during a vehicle test, it is desirable to restrain the vehicle on the test stand. One test stand restraining device has been proposed that requires the test stand operator to position a plurality of individual blocking devices, one blocking device in front of and one behind each tire. Once the vehicle and each of the blocking devices are positioned properly on the test stand, the operator must bolt each of the blocking devices in place to the test stand frame. After the test of the vehicle is completed, the operator must unbolt and remove each of the blocking devices to permit the vehicle to be driven off of the test stand. The use of such a restraining device is extremely time consuming and costly.